The first aspect of the invention relates to a medical fluid passage switching apparatus and particularly to a fluid passage switching apparatus mounted to a Y-shaped connecting tube in a continuous ambulatory peritoneal dialysis (CAPD) system, as shown in FIG. 4.
The second aspect of the invention relates to components of the medical fluid passage switching apparatus of the first aspect and particularly to a tube employed in the apparatus.
The third aspect of the invention relates to a CAPD system employing the medical fluid passage switching apparatus of the first aspect or the medical fluid passage switching apparatus equipped with the tube of the second aspect.
(1) In a conventional back-free, twin-bag system of the CAPD technology, it is necessary to operate three clamps K1, K2, and K3 in a specific order shown in Table 1, wherein said clamp K1 is mounted to a first tube 1 connected at one end to a catheter implanted in the body of a patient, said clamp K2 is mounted to a second tube 2 connected at one end to a Y-shaped joint 4 joined to the other end of the first tube 1 and at the other end to a dialysis liquid bag 5 for supplying a fresh charge of a dialysis liquid to the patient, and clamp K3 is mounted to a third tube 3 connected at one end to a drain bag 6 for collecting and discarding the charge of the dialysis liquid stored in a peritoneal cavity of the patient for a given period of time.
In the table, the number of steps is denoted by the arrow symbolxe2x80x9c↓xe2x80x9d.
For completing a sequence of the steps, the patient must carry out eight actions for opening and closing the clamps. Those actions are troublesome and may be performed improperly. Also, this will discourage the application of the conventional system for a new, unskilled patient. For solving the above problems, a novel technique is developed and disclosed in PCT unexamined Japanese Publication (Tokko-Hei) 2-502882.
(2) The technique disclosed in PCT unexamined Japanese Publication (Tokko-Hei) 2-502882 has an actuator of substantially a cylindrical shape installed in substantially a tubular housing and is connected to a valve having three ports which are in turn communicated to a first, a second, and a third tube. The valve is actuated between four positions: a position for shutting off all the ports, a position for ensuring a passage is available for fluid between the first and second ports, a position for ensuring a passage is available for fluid between the second and third ports, and a position for ensuring a passage is available for fluid between the first and third ports.
However, such an arrangement requires extra means for ensuring the air-tightness and liquid-tightness in both the actuator and the housing. If the air-tightness and liquid-tightness is imperfect, bacteria existing in the air may enter the peritoneal cavity, hence causing peritonitis. According to the previous invention, the actuator and the cylindrical housing are sealed to have air-tightness and liquid-tightness with the use of O-rings which are still unsatisfactory.
A first object of the present invention is to provide a fluid passage switching apparatus in a medical system and particularly a fluid passage switching apparatus in a CAPD system, which at least comprises: a rotatable shaft; a cam which is rotated in relation to the rotating movement of the shaft to close and open each tube for determining the passage of fluid; and a housing so arranged to enable the holding of the cam, and having holes for running each tube therein, wherein said each tube communicating one another, and said cam consists of one member to close and open each tube for determining passages, whereby a series of fluid passage switching actions can be carried out with easier, and more particularly, to provide a fluid passage switching apparatus in a CAPD system in which a series of fluid passage switching actions can easily be carried out without producing leakage of the fluid and suffering from microbism.
A second object of the present invention is to provide a fluid passage switching apparatus having an improvement of the fitting structure of the housing in the fluid passage switching apparatus of the first object, where the housing is assembled with high accuracy to have precise dimensions but with much ease and with little chance of disassembly after initial assembly, hence giving a good enough level of safety.
A third object of the present invention is to provide a tube capable of minimizing the overall dimensions of the fluid passage switching apparatuses of the first and second objects.
A fourth object of the present invention is to provide a fluid passage switching apparatus which is improved in installing a plurality of clamps which are commonly used in each of the fluid passage in switching apparatuses of the first and second objects, are small in size, and assembled without much difficulty, for clamping the tubes, thus avoiding any assembling fault, such as the absence of a clamp.